Takt time vs cycle time vs lead time: calculate the right clock
A worked shift example separates customer pace, observed process speed and end-to-end delivery time, with practical checks before changing the line.
Rational subgroup
A sampling group designed so within-group variation represents the short-term variation being studied.
Samples might come consecutively from one machine or cavity while between-group differences expose changes over time. Mixing different streams inside every subgroup can conceal the changes of interest. Retain stream and time identity with raw data, and document how the within-subgroup variation estimate was obtained. See capability indices.
See also: Statistical process control (SPC) · Process capability
Use the concept: Sample mean & standard deviation calculator · Cp, Cpk, Pp & Ppk calculator · Downtime log template
In depth
SMED changeover study: measure last good to first good
Use a time observation sheet to separate internal and external work, preserve safe setup steps, and verify a repeatable changeover improvement.
Automation ROI and payback: a business case operations can verify
Separate installed cost, cash savings, released capacity and recurring expenses, then test a conservative scenario before approving automation.